Structure of putative epidermal sensory receptors in an acoel flatworm, Praesagittifera naikaiensis

We examined the three-dimensional relationship between epidermal sensory receptors and their innervation in an acoel flatworm,Praesagittifera naikaiensis. The distribution of the sensory receptors was different between the ventral and dorsal sides of worms. The nervous system was mainly composed of a peripheral nerve net, an anterior brain, and three pairs of longitudinal nerve cords. The nerve net was located closer to the body surface than the brain and the nerve cords. The sensory receptors have neural connections with the nerve net in the entire body of worms. We identified five homologs of polycystic kidney disease (PKD):PKD1-1,PKD1-2,PKD1-3,PKD1-4, and,PKD2, from theP. naikaiensis genome. All of thesePKD genes were implied to be expressed in the epidermal sensory receptors ofP. naikaiensis.PKD1-1 andPKD2 were dispersed across the entire body of worms.PKD1-2,PKD1-3, andPKD1-4 were expressed in the anterior region of worms.PKD1-4 was also expressed around the mouth opening. Our results indicated thatP. naikaiensis possessed several types of epidermal sensory receptors to convert various environmental stimuli into electrical signals via the PKD channels and transmit the signals to afferent nerve and/or effector cells.
Source: Cell and Tissue Research - Category: Cytology Source Type: research